Design, prototyping and testing of a compact superconducting double quarter wave crab cavity

TL;DR

This paper presents the design, fabrication, and testing of a novel compact superconducting double quarter wave crab cavity with high deflecting voltage suitable for LHC upgrades.

Contribution

It introduces a new DQWCC design that is compact, operates at 400 MHz, and achieves a deflecting voltage above the requirements for HL-LHC.

Findings

Achieved a deflecting voltage of 4.6 MV

Successfully fabricated and tested a superconducting niobium cavity

Demonstrated electromagnetic properties suitable for LHC upgrade

Abstract

A novel design of superconducting Crab Cavity was proposed and designed at Brookhaven National Laboratory. The new cavity shape is a Double Quarter Wave or DQWCC. After fabrication and surface treatments, the niobium proof-of-principle cavity was cryogenically tested in a vertical cryostat. The cavity is extremely compact yet has a low frequency of 400 MHz, an essential property for service for the Large Hadron Collider luminosity upgrade. The electromagnetic properties of the cavity are also well matched for this demanding task. The demonstrated deflecting voltage of 4.6 MV is well above the requirement for a crab cavity in the future High Luminosity LHC of 3.34 MV. In this paper we present the design, prototyping and test results of the DQWCC.